ZIOPHARM Oncology, Inc. (Nasdaq: ZIOP) announced the presentation of preliminary data from the Company’s Phase 1b/2 study of Ad-RTS-hIL-12 + veledimex following standard chemotherapy for the treatment of patients with locally advanced or metastatic breast cancer. The poster presentation, titled “Phase 1b/2 study of intratumoral Ad-RTS-hIL-12+veledimex in patients with chemotherapy-responsive locally advanced or metastatic breast cancer,” was presented at the European Society for Medical Oncology (ESMO) 2016 Congress today in Copenhagen, Denmark.

The study, which is being conducted at the Memorial Sloan Kettering Cancer Center in New York, is designed to examine the safety, tolerability and efficacy of Ad-RTS-hIL-12 immunotherapy in up to 40 women with locally advanced or metastatic breast cancer of all subtypes. Ad-RTS-hIL-12 + veledimex is a novel gene therapy which controls local expression of IL-12. The ability to regulate the production of IL-12 by modulating veledimex dosing is designed to improve its therapeutic index with standard of care.

Following entry into the trial, patients go on a chemotherapy holiday and enter an immunotherapy phase of treatment. A single cycle of Ad-RTS-hIL-12, along with the oral activator ligand veledimex, is given during the immunotherapy phase, with the goal of maintaining or improving pre-study response.

As of August 30, 2016, a total of nine patients were available for initial assessment. Results show that Ad-RTS-hIL-12 + 7 days of veledimex consistently elicited production of IL-12 which in turn produced IFNγ. It was notable that the intratumoral influx of CD8+ T cells and IFNγ were present six weeks after completion of veledimex consistent with the ability of Ad-RTS-hIL-12 to favorably impact the tumor environment over the long term. In two patients, Ad-RTS-hIL-12 + veledimex provided a meaningful drug holiday, with durable responses for 18 and 35 weeks. In all patients, disease control rate (DCR) was 44% at Week 6 and 22% at Week 12. Overall response rate (ORR), defined as achieving a partial response (PR) or better, was 11% at Week 12. Most toxicities promptly reversed upon discontinuation of veledimex, including cytokine release syndrome (grade 1-2 CRS), observed in six of nine patients. The higher than expected incidence of CRS was likely related to CYP-3A4 drug interactions with veledimex (80 mg) which resulted in enhanced peak cytokine expression.

“These data provide additional evidence that IL-12 expression and corresponding downstream signaling is activated using Ad-RTS-hIL-12 + veledimex, consistent with results observed in other studies and tumor types,” said Francois Lebel, M.D., Executive Vice President, Research and Development, Chief Medical Officer at ZIOPHARM. “Early results from this study are promising, providing further support and validation for our ongoing study of Ad-RTS-hIL-12 in glioblastoma, a program we anticipate moving into a pivotal trial.”